Method for Configuring Field Devices

ABSTRACT

The invention relates to a method for configuring field devices in a process automation system wherein the field devices are connected to other automation components by means of a field bus. In order to minimize the load placed on the field bus, a copy of the current configuration of each field device is stored in a configuration tool, the appropriate set of configuration and parameter data is transmitted to each field device during initial start-up and modifications in relation to the previous copy of the configuration and parameter data are transmitted to the respective field device.

The invention relates to a method for configuring field devices in a process automation system.

Modern process automation systems as used in the chemical, petroleum and other process industries employ intelligent field equipment, sensors and actuators. These field devices, as they are known, are connected together and to the rest of the process automation system components via a fieldbus system or other communications installations.

The automation functions, which are essentially control loops, are distributed across these field devices. The potential use in hazardous areas, in particular, places limits on the resources of the field devices for storing the configuration and parameters, and on the transmission bandwidth of the fieldbus systems. A configuration tool having a central configuration database is used for configuring and parameterizing the process automation system. This configuration tool can be used to configure the process automation functions, including the configurations and parameters of the field devices, before any communications link has been established with the field devices (offline configuration). In a subsequent step, the configuration tool is then connected to the fieldbus, and the configurations and parameters are downloaded to the field devices. This download process must include synchronization with data already held in the device, for example preconfigured data.

The configuration is generated on the basis of device description data in order to take into account the specific properties of the field devices. This device description data is normally kept in machine-readable form as a file.

Process automation systems are used for critical, continuous processes, in which the automation function can only be stopped in certain situations. The use of resource-limited field devices on a fieldbus with a highly restricted bandwidth requires special techniques in order to be able to download changes in configuration data and parameter data to the field devices via the fieldbus, even during normal operation, without stopping the automation function.

The object of the invention is to define a method for configuring field devices in the process automation system, wherein the loads placed on the communications links are minimized.

This object is achieved according to the invention by the features of claim 1. Advantageous embodiments of the invention are given in the dependent claims.

The invention is based on a configuration tool having a central configuration database, where the said configuration tool can be used to configure the process automation functions, including the configurations and parameters of the field devices, before any communications link has been established with the field devices. The invention is also based on the condition that all configurations are set in the configuration tool.

The configuration tool uses copies of field-device configuration data and parameters, which reflect the most recent download status of the field devices. Such a copy is recorded once only for each field device.

According to a further feature of the invention, in order to check the version of the copies of the configuration data with the field-device data, instead of a complete configuration and parameter comparison, the configuration tool uses version IDs, which either are managed by the field device itself and changed implicitly by download operations, or are downloaded to the field devices with the configuration data by the configuration tool, and hence can be used for identifying the configuration held in the field device.

Configuration changes are copied by the configuration tool into the configuration entries and parameter entries of the field devices in such a way as to minimize the impact on the running process automation functions of the whole system, and also to reduce the download operations required until the new configuration in the field devices is obtained.

To achieve this, a copy of the most recently downloaded configuration of each field device is initially stored in the configuration tool in a once-only step. By this means, even field devices already integrated in the process automation plant and in operation can subsequently be included in the configuration by means of said configuration tool.

Field devices being added are provided initially with the minimum configuration data and parameter data required for first-time start-up. This data constitutes the most recently downloaded configuration of the field device and is consequently stored as the copy in the configuration tool.

Subsequently, configuration changes and parameter changes from the configuration tool are only transferred as increments to the most recently downloaded configuration.

The increments are generated in the configuration tool on the basis of copies of field-device configuration data, which reflect the most recent download status of the field devices. The increments are chosen here so as to minimize the impact on the process controlled by the system and also to minimize the transmission times by changes being as small as possible.

In detail, this is achieved as follows: initially, a copy of the current configuration of each field device is stored in the configuration tool; in the next step, the difference is determined between the current configuration and the most recently downloaded configuration of the same field device; finally, the determined difference is transmitted to the respective field device for updating the configuration data and parameter data as required. These three steps are repeated recursively for each new configuration.

The generated configuration may use, for implementing the same automation function, more configuration entries than a configuration that does not take account of the current configuration of the field devices. This means, however, that the download operations required to obtain the new configuration in the field devices can be reduced, and the impact on the process automation function of the whole system can be minimized.

By means of the method described here, changes that were made without a communications link to the field devices (offline) can be incrementally downloaded to the devices or synchronized with the data held in the devices, without needing to interrupt the process automation function of the whole system.

According to a further feature of the invention, it is provided to assign a version ID to each copy of a configuration. This simplifies management of a large number of configurations in the configuration database.

According to a further feature of the invention, it is provided that the version IDs are managed by each field device itself, or are changed implicitly by download operations.

According to a further feature of the invention, it is provided that the version IDs are downloaded to the field devices with the configuration data by the configuration tool.

In this case, it can be provided that the extent of the as-required update of the configuration data and parameter data is determined by the configuration tool from the version IDs and the copy of the most recently downloaded configuration.

In a preferred embodiment of the invention, the version IDs are graded. The grading is based on the knowledge that a device configuration for a modern, complex field device has a certain detectable granularity that is reflected in properties of objects. In this case it is provided that, in addition to the situation where the whole configuration has changed, the change in objects is also identified if at least one property has changed.

The extent of the as-required update of the configuration data and parameter data is determined dynamically from the grades of the version IDs by establishing those objects whose properties have been changed. This advantageously simplifies the process of determining the required update extent. 

1. A method for configuring field devices in a process automation system, in which the field devices are connected to other automation components via a fieldbus, which makes use of a configuration tool, wherein a copy of the most recently downloaded configuration of each field device is stored in the configuration tool in a once-only step, and the following steps are repeated recursively: storing a copy of the current configuration of each field device in the configuration tool, determining the difference between the current configuration and the most recently downloaded configuration of the same field device, and transmitting the determined difference to the respective field device for updating the configuration data and parameter data as required.
 2. The method as claimed in claim 1, wherein at start-up the minimum set of configuration data and parameter data required for an initial start-up is transmitted to each field device.
 3. The method as claimed in claim 1, wherein a version ID is assigned to each copy.
 4. The method as claimed in claim 3, wherein the version IDs are managed by each field device itself and are changed implicitly by download operations.
 5. The method as claimed in claim 3, wherein the version IDs are downloaded to the field devices with the configuration data by the configuration tool.
 6. The method as claimed in claim 3, wherein the extent of the as-required update of the configuration data and parameter data is determined by the configuration tool from the version IDs and the copy of the most recently downloaded configuration.
 7. The method as claimed in claim 6, wherein the version IDs are graded, and the extent of the as-required update of the configuration data and parameter data is determined dynamically from the grades of the version IDs.
 8. The method as claimed in claim 2, wherein a version ID is assigned to each copy.
 9. The method as claimed in claim 5, wherein the extent of the as-required update of the configuration data and parameter data is determined by the configuration tool from the version IDs and the copy of the most recently downloaded configuration.
 10. A method for configuring at least one field device in a process automation system, in which the at least one field device is connected to other automation components via a fieldbus, which makes use of a configuration tool, comprising: storing a copy of a current configuration of the at least one field device in the configuration tool; determining the difference between the current configuration and a most recently downloaded configuration of the respective one of the at least one field device; and transmitting the determined difference to the respective one of the at least one field device for updating configuration data and parameter data as required. 